Shock-absorbing typebar stop



Feb. 13, 1968 E. R. MUMPOWER 3,368,659

SHOCK-ABSORBING TYPEBAR STOP Filed April 5, 1967 22 FIGJ I 1 WI 1% 24"ii i 30 28 v2o 26 J-' INVENTOR 4 HIS ATTORNEYS United States Patent3,368,659 SHOCK-ABSORBHWG TYPEBAR STOP Erle R. Mumpower, Kettering,Ohio, assignor to The National Cash Register Company, Dayton, Ohio, acorporation of Maryland Filed Apr. 3, 1967, Ser. No. 628,092 2 Claims.(Cl. 19742) ABSTRACT OF THE DISCLOSURE A shock-absorbing stop tominimize rebound of typewriter levers. The stop includes anarcuately-shaped member which is yieldably supported near each end onspringloaded pins for movement towards a similarly-shaped supportmember. Each lever, upon returning to a home position after printing,strikes an elastomer strip secured to the movable member and moves ittowards the support member to thereby prevent rebound of the lever andminimize the noise of impact.

Background of the invention This invention relates to a shock-absorbingstop, and, more particularly, it relates to a shock-absorbing stop whichis especially adaptable for use with typewriter levers to prevent therebounding thereof when the levers return to a home position afterhitting the platen of the typewriter or similar machine in which thestop is used.

Resilient shock-absorbing stops to prevent typewriter lever rebound areknown; however, the prior-art constructions wear rapidly when subjectedto extensive use. This is especially true when the prior-artconstructions are used with electric-power-0perated typewriters, whosereturning typewriter levers have comparatively large amounts of kineticenergy to be transferred to the shockabsorbing stops upon impactthereagainst. Because the electrically-operated typewriters operate athigh speeds, it is also necessary that the shock-absorbing stops usedtherewith quickly absorb the kinetic energy of the returning levers.

The shock-absorbing stop of this invention quickly absorbs the impactenergy of typewriter levers returning to a home position after strikingthe platen of the typewriter in which the stop is used. Said stop isinexpensive to produce and has sufficient flexibility and responsivenessto be effective even when used with light-weight typewriter levers whichare operated at high speeds.

Summary of the invention The shock-absorbing stop of this inventionincludes a .first elongated member, which has end portions adapted to besecured to a support in a typewriter or other similar printing machinewith which said stop may be used. The stop also includes a secondelongated member, having first and second opposed sides thereon with astrip of resilient material secured to said first side. When said stopis used in a typewriter, the typewriter levers actually rest upon saidstrip when the levers are idle, or in the home position. The stop alsoincludes resilient means secured to said second side for yieldablymaintaining said second member in spaced relation with said firstmember, whereby at least a portion of said second member is movedtowards said first member when one of said typewriter levers impactsagainst said strip in returning to said home position after striking theplaten in the machine in which the stop is used.

Brief description of the drawings FIG. 1 is a side view in elevation ofthe shock-absorbmg stop of this invention as used in a typewriter.

3,368,659 Patented Feb. 13, 1968 Description of the preferred embodimentFIG. 1 shows the shock-absorbing stop 10 of this invention as used in atypewriter. The levers 12, 14, 16, and 18 are connecting levers used toactuate the typewriter levers 20 to move them individually to strike theplaten 22. Because said connecting levers are conventional and do notform a part of this invention, they are shown only generally, so as toorient the stop 10 within the structure of a typewriter. The levers 20are shown in the home position, resting on the resilient strip 24 of thestop 10. After each individual lever 20 is actuated to strike the platen22, it rebounds therefrom to impact against the stop 10, which isadaptable to quickly absorb the kinetic energy of the impacting lever20.

The construction of the shock-absorbing stop 10 is best shown in FIG. 2.The stop 10 includes a first, generally arcuately-shaped, elongatedmember 26, having end portions 28 adapted to be secured to a support 30(FIG. 1) by fasteners 32. Positioned adjacent to said first member 26 isa second, generally-arcuately-shaped, elongated member 34, which has theresilient strip 24 secured to one side thereof by conventionaladhesives. The strip-24 is made of elastomeric material, such as vinylchloride, and, in the embodiment shown, was approximately inch thick.

The second elongated member 34 is yieldably held in spaced relation tothe first elongated member 26 by the following construction. Each end ofthe elongated member 34 is secured to the elongated member 26 by aresilient means 36, having the arrangement shown in FIG. 4, whichincludes a stud or pin 38 projecting from one side of said member 34.The stud 38 extends through a slot 40 in the first elongated member 26,anda compression-type spring 42 is mounted on the stud between themembers 34 and 26, suitable washers 44 being positioned on the stud onopposite sides of the slot 40 in the member 26, as shown. A secondcompression-type spring 46, producing slightly less compression than thespring 42, is also mounted on the stud 38 between one of the washers 44and a washer 45, a retaining C-shaped clip 48 being used to retain thespring 46 on the free end of the stud 38. By this construction, the areanear each end of the second elongated member 34 is provided with aresilient means 36, which may act as a pivot point for the opposite endof said member 34 when a typewriter lever 20 strikes said opposite end.Also included in this construction is a third stud 52, which projectsfrom the second member 34 (FIGS. 2 and 3) and passes through an opening50 in the'first member 26; both sides of the opening 50 are countersunk.

The operation of the stop 10 is as follows. When an object, such as atypewriter lever 20, strikes the resilient strip 24 near one of theresilient means 36 (the one shown in the left side of FIG. 2, forexample), its spring 42 is compressed somewhat against its bias, and thesecond member 34 is resiliently moved towards the first member 26,thereby absorbing some of the kinetic energy of the impacting lever 20.Some of said energy is also absorbed by the resilient strip 24, whichdeadens some of the noise of impact. In addition, when the left end ofthe member 34 (as viewed in FIG. 2) moves toward the member 26, theright end of the member 34 is moved slightly away from the member 26 dueto a slight pivoting of the member 34 about the stud 52, which islocated approximately in the center of the length of the member 26. Innormal operation, all the typewriter levers 20 rest upon the resilientstrip 24, as shown in FIG. 1; however, when one end of said member 34moves away from the member 26, as mentioned in the previous sentence,the levers 20 resting on said one end are also moved with it, therebyabsorbing some of the said kinetic energy. The springs 46 then assist inrestoring the second member 34 to the static position, shown in thedrawings. When a lever 20 impacts against said resilient strip 24 nearthe center of the second member 34, the center of the member 34 (nearthe stud 52) moves toward the member 26 against the bias of the springs42 to absorb most of the kinetic energy of impact. The resilient strip24 also absorbs some of the kinetic energy.

The particular size of the springs 42 and 46 and the other elements inthe stop are determined by the particular application in which the stopis used. The particular stop 10 shown herein is responsive enough to beused with typewriter levers 20, which are considered lightweight in theart.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein Without departing from the spirit and scope of theinvention.

What is claimed is:

1. A shock-absorbing stop adapted to be secured to a support andcomprising:

a first elongated, arcuately-shaped member having end portions adaptedto be secured to said support;

a second elongated, arcuately-shaped member having first and secondopposed sides thereon, and first and second opposed ends;

a strip of elastomer material secured to said first side of said secondmember;

a stud projecting from said second side near each said end of saidsecond member;

said first member having slots therein to receive said studs, with eachsaid stud being of sufficient length to provide a section which extendsthrough and beyond its pertaining said slot;

a first compression-type coil spring mounted on each said stud betweensaid first and second members;

a second compression-type coil spring mounted on each said sectionbetween said first member and the free end thereof; and

fastener means to secure said second springs on the free ends of saidsections and to subject all said springs to a slight compression;

said slots being of sufiicient size to enable one end of said secondmember to move towards said first member against the bias of at leastsaid first springs when an object impacts said strip near said one endwhile said second member is pivoted about a point near its opposite end.

2. The stop as claimed in claim 1 in which all said first springsprovide a slightly greater compressive force 7 than said second springsand yieldably maintain said second member in spaced arallel relationwith said first member, and in which said first member has a hole in thecenter thereof, said second member also having a third stud projectingfrom said second side thereof and adapted to extend through said hole toassist in maintaining said second member in said spaced parallelrelation with said first member, and to provide 'a pivot point for saidsecond member when an object impacts said strip near one said end ofsaid second member.

References Cited UNITED STATES PATENTS 884,347 4/1908 Yetman l97--42 XR886,570 5/1908 Young 197-42 2,043,393 6/1936 Pasinski l9742 XR 2,176,12310/ 1939 Denzer 197-42 ROBERT E. P-ULFREY, Primary Examiner.

E. S. BURR, Examiner.

